Dynamics of Sulfate-Reducing Bacteria Community Structure in Surface Sediment of a Seasonally Hypoxic Enclosed Bay

• Published in: Microbes and Environments Vol. 33; no. 4; pp. 378 - 384
• Main Authors: Mori, Fumiaki, Umezawa, Yu, Kondo, Ryuji, Wada, Minoru
• Format: Journal Article
• Language: English; Japanese
• Published: Japan Japanese Society of Microbial Ecology / Japanese Society of Soil Microbiology / Taiwan Society of Microbial Ecology / Japanese Society of Plant Microbe Interactions / Japanese Society for Extremophiles 2018; Japan Science and Technology Agency; the Japanese Society of Microbial Ecology (JSME)/the Japanese Society of Soil Microbiology (JSSM)/the Taiwan Society of Microbial Ecology (TSME)/the Japanese Society of Plant Microbe Interactions (JSPMI)
• Subjects: Bacteria; Bottom water; Communities; Community structure; Dissolved oxygen; Dynamics; enclosed bay; Gene polymorphism; Gene sequencing; Hypoxia; Polymorphism; Reductases; Restriction fragment length polymorphism; rRNA 16S; Sediment; Sediment samplers; Sediment samples; Sediments; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulfite; Sulfite reductase; Sulphate reduction; T-RFLP; hypoxia; sulfate-reducing bacteria; enclosed bay; T-RFLP; sediment
• ISSN: 1342-6311; 1347-4405
• DOI: 10.1264/jsme2.ME18092

We herein report on the dynamics of a sulfate-reducing bacteria (SRB) community structure in the surface sediment of a seasonally hypoxic enclosed bay for two consecutive years (2012 and 2013). The uppermost (0–5 mm) and subsurface (5–10 mm) layers of sediment were examined with a terminal-restriction fragment length polymorphism (T-RFLP) analysis based on the dissimilatory sulfite reductase (dsrA) gene. The SRB community significantly differed between the two sediment layers over the sampling period. This difference was mainly attributed to operational taxonomic units (OTUs) that were unique to either of the sediment layers. However, nearly 70% of total OTUs were shared between the two layers, with a few predominating. Therefore, no significant shift was observed in the SRB community structure under varying dissolved oxygen (DO) conditions in bottom water overlying the sediment surface. An additional analysis of 16S rRNA gene amplicon sequences, conducted for three uppermost sediment samples (July, August, and September in 2012), revealed that Desulfococcus, a member of SRB with high tolerance to oxygen, was the predominant Deltaproteobacteria across the uppermost sediment samples. Based on the predominance of shared OTUs across the SRB community in the sediment (0–10 mm) regardless of bottom-water DO, some SRB that are physiologically tolerant of a wide range of DO conditions may have dominated and masked changes in responsive SRB to DO concentrations. These results suggest that the SRB community structure in the enclosed bay became stable under repeated cycles of seasonal hypoxia, but may be compromised if the severity of hypoxia increases in the future.